The data processing power and speed of modern computer systems depend to a great degree on the efficient control and removal of heat energy from the computer's electronic components. This problem becomes even more significant in light of improvements in the emitter-coupled logic (ECL) and complementary metal-oxide semiconductor (CMOS) integrated circuit fabrication processes, resulting in VLSI components that typically generate large amounts of heat. The heat dissipated by these components, if not effectively controlled and removed, could severely reduce the reliability of the components and systems.
While control and removal of heat energy relates dramatically to computer operation, this problem also has substantial bearing in other electronic component applications having critical reliability requirements, for example in the area of avionics, aerospace and the military.
The use of air flow, whether natural or driven, is a simple and traditional means of cooling. The principle of mass flow of air, where a cool air stream is blown or drawn across the surface of heat-generating components, results in the layer of air closest to the hot surfaces accepting heat from the components and displacing it. For many mass air flow cooling methods, much of the air stream does not significantly contribute to the heat removal process. The air movement device, such as a fan, pushes more air than is useful in the process, resulting in an inefficient method. Consequently, the harnessing of air flow to maximum efficiency would effect significant improvement in the design and operation of the cooling process.
Prior attempts to improve the efficiency of air flow cooling include air impingement designs. Air impingement implies the directing of cooling air onto heat generating objects by means of channeling or air ducting. Such air impingement designs are based on the principle of air motivation, with a blower being the usual means of moving the air.
An attempt has been made to utilize air impingement cooling for providing a heat transfer mechanism for an electronic circuit module assembly. Such an arrangement is disclosed in U.S. Pat. No. 4,277,816 issued to Dunn et al on July 7, 1981, entitled "Electronic Circuit Module Cooling." Dunn et al utilizes air directed under positive pressure to remove heat from electronic circuit modules mounted on a circuit board assembly. An air plenum chamber is mounted adjacent the circuit board assembly, with a plurality of openings therein, one for each electronic circuit module of the assembly. Air passes into the air plenum and is directed through the openings into heat sinks of each electronic module, causing air turbulence within the heat sinks. The spent air, after escaping from within the heat sinks, is exhausted through channels defined between the electronic modules in a manner such that the spent air has minimal impingement on adjacent modules. Although the air plenum can be designed to be relatively air tight, after the air is directed therefrom onto the module to be cooled, there is no requirement to maintain air tightness within the system.
However, the spent air, after having been warmed by removing heat from a heat sink, may degrade the ability of the impinging cooling air to remove heat from another or adjacent heat sink. Although such cross flow degradation can be remedied by increasing the volume of impinging air supplied, the efficiency of the cooling arrangement may be degraded, since more energy is required to propel the larger air volume.
An alternate attempt has been made to utilize air impingement cooling for providing an air cooling arrangement for a column of integrated circuit modules in a computer frame. Such an arrangement is disclosed in U.S. Pat. No. 4,233,644 issued to Hwang et al on Nov. 11, 1980, entitled "Dual-Pull Air Cooling for a Computer Frame." Hwang et al utilizes a pair of air moving devices to pull air through the column. Air flow guides extend from a cover plate having openings therein to allow air to pass into heat sinks attached to the modules and confine the air flow to a vertical impinging pattern. Air distribution ducts are arranged on opposite sides of the heat sinks facilitating exhausting of spent air.
In many instances, however, the air cooling arrangement as described above may required major cabinet level redesign of existing computer frames and possibly, component level changes.
Therefore, in accordance with an aspect of the present invention, a feature is to provide a new and improved method and apparatus for controlled air impingement module cooling of electronic components mounted to a circuit board.
In accordance with another aspect of the present invention, a feature is to provide an efficient method and apparatus of air impingement exhaust which prevents degradation of the impingement system upon other components mounted to the circuit board.
A further feature of the present invention is to provide a method and apparatus for controlled air impingement module cooling that eliminates the need for major computer cabinet redesign.